Flexibly mounted and connected vertical gas heating furnace



Patented Apr. 17, 1951 FLEXIBLY MOUNTED AND CONNECTED VERTICAL GAS HEATING FURNACEl Walter Huber, Winterthur, Switzerland, assignor to SulzerFreres, Societe Anonyme, Winterthur,

Switzerland ApplicationSeptember 7, 1946, Serial No. 695,432 In Switzerland December 18, 1945 7 Claims. l

This invention relates to a gas heater in which the heating gas flows through two tube nests connected in series by a U-bend and arranged vertically over the bend. Y

The invention is characterised in that the jack'- ets surrounding the tube nests and taking the pressure of the gas to be heated', are connected to `each other by means of a rigid U-bend, that further the bend connecting the tube nests with each other is formed yielding and is arranged with play inside the rigid bend, and that nall'y the pressure jackets are supported yieldingly on a base in such away that` their distance apart can change in accordance with the heating of the rigid U--bend connecting them.

The gas heater according to the invention is particularly suitable for adoption in gas turbine plants in which the gases to be heated must attain a very high temperature. of the temperature drop occurring with heat transmission,l differences occur in the thermal eX- pansion of the separate structural parts. Such differences in expansion may be compensated particularly easily in gas heaters according to the present invention. The invention is further described below with reference to the example illustrated in the drawing, the single figure of which comprises a side elevatiom partly in section, of the device.

The two vertically arranged tube nests I and 2, which are connected` in series by means of a U-bend 3 serve as heat exchange surfaces of the gas heater illustrated. The heating gases flow first of all through the tubes of the nest I and then pass through the U-bend into the tubes ofV `the nest 2. The jackets 4 yand 5 surrounding the nests and taking the pressure of the gas to be heated, are connected to each other by means of a U-bend 6, which is of rigid construction. In contrast to that, the U-bend 3 connecting the tubes together is formed yielding and arranged inside the rigid bend B in such a way that it has free play in every direction. The supporting of the pressure jackets is effected by the feet 'I and 8, the feet 'I being xed by means of bolts 9 to the floor I0, whilst the feet 8 can slide over the floor in correspondence to the expansion of the bend 6. The distance between the two nests of tubes I and 2 and their supporting jackets 4 and 5 may therefore change according` to the amount of heating of the rigid U-bend I5.

The gas to be heated-for example air-hows from the pipe IIl into the branch I2 of the jacket 5. In the space I4 betweenthe pressure jacket 5 and the guide jackets I3 this gas flows first of all In consequence upwards so that at the spot I5 it enters the space I6: formed betweenV the tubes of the nestV 2 and then flows downwards along the tubes within the guide jacket I3. At the spot II the gas issues again from the space within the nest of tubes and passes finally into the pressure jacket 4 through the passage I 8 formed between the U-bends 3 and 6. Here, the gas passes through the openings I9 of the guide jacket 2l) into the space 2I surrounding the tubes of they nest I. The openings 22 allow the finally heated gas to issue into the `annular space 23 formed between the jackets 4 and 2D. Through the branch 24 the pressure jacket 4 is connected to a pipe 25 which leadsv the heated gas tov a spot where it is used, not shown in the drawing.

The tube nest I? is connected at the top to the combustion chamber 26, which is surrounded pressure-tight by the covering bell 4"` of the pres sure jacket 4. Fuel is introduced and atomised through a burner 2l. The combustion air hows out of the pipe 28 through the branch 29 into the annular space 30 and then passes at the spot 3l into the combustion chamber 2E. The secondary air required for perfect combustion Hows out of the pipe 32' through the branch 33 into the annular space 34 and passes through the openings 35 into the flame present in the combustion chamber 26.

The combustion gases flow through the tubes of the tube nest I into the U-bend 3 and from there through the tubes of the tube nest 2 into the collecting space 36 and into the exhaust gas pipe 3l. When flowing through the tube-s ofthe tube nests I and 2 a considerable part of4 the heat contained in the combustion gas is transmitted by heat exchange to the gas surrounding the tubes and the nests. In this way the combustion gas cools, whilst the gas to be heated is brought up to the desiredl temperature.

The tube nests I and 2 are supported by the pressure jackets 4 and 5 respectively. The weight of the tubesof the nest I is lirst of. all transmitted through the cone-shaped tube plate 38 tov the guide jacket 20 which in its turn is supported by the flange 39 on the supporting ring 4Il of the jacket 4. For separating the space 2i surrounding the tubes of the nest I from the annular space 34 that connects, with the combustion chamber 26, a yielding bellows 4I is provided, which is connected at `one end to the flange 39 and at the other to the upper tube plate 42 of the nest I. The weight of the tube nest 2 is supported on the upper ange of pressure jacket 5 by means of `a pipe line. able also for fairly high pressures, for instance Ilange 14 of a cone-shaped upper tube plate 49 which in turn supports the closing bell I).

For cooling the tube plate 42, which is very strongly heated by the flame in the combustion space 26, the tube nest I contains in the middle a'wide tube 43 which is provided Awith .openings 44 and 45. A part of the gas flowingin through the openings I9 then ows through the openings 44 into the tube 43 and leaves it again through the' openings 45 without becoming heated to any extent worth mentioning, and then flows along the tube plate 42 towards the outlet opening 22. In this way the cooling of the tube plate and of the top parts of the tubes is rendered more effec- Y tive.

The weight of the jacket 46 of the combustion chamber is supported on the pressure jacket 4. Between the jacket 46 and the connecting piece ni o 41 fastened to the tube plate 42 of the tube nest Y I, a sliding connection 43 is provided in order to nest I has a surrounding centering ring52 connected to it with separate straps 53. A corresponding ring 54 is fixed by means of straps 55 to the inside of pressure jacket 4. These two vrings 52 and 54 serve for centering the lower end of tube nest I in the pressure jacket 4.

Y The U-bend 3 consists of three part bends 56, 51 and 58 which are connected to each other by means of the joints 59 and 60 and the bellowslike yielding pieces 65 and 66. Inthis way an amount of yielding is obtained, so that the differences in expansion between the two U-bends 3 and 6 can be easily compensated, without causing any great stresses by bending at the joints 59 and 60 and in the tube nest 2.

The connecting flanges 61 and 63 between the rigid bend 6 and the pressure jackets 4 and 5 are arranged higher than the connecting flanges 69 and between the yielding U-bend 3 and the tube nests I and 2. After loosening the connecting flanges 61 and 68 the rigid U-bend can be lowered by the amount h until it comes .to rest with the feet 1I on the floor 12. The distance i between the saddle of the rigid U-bend 6 and the saddle of the yielding U-bend 3 is chosen greater than the height h, so that also in the lowered position the two U-bends do not touch each other. The flanges of the U-bend'l` are then in the position 6 shown in broken lines, in which position the connecting flanges 69 and 'I0 between the flexible U-bend 3 and the tube nest IV and 2 are freely exposed and can also be loosened. The two U-bends may now be removed together after which the tubes of the nest I and 2 are accessible for cleaning and inspection.

For dismantling the tube nests, rst of all the top parts of the pressure jackets 4 and 5 are loosened at the flanges 13 and 14 and removed. After this the jacket 46 of the combustion chamber 26 and the tube nest l and 2 can be removed upwards.

The combustion chamber may also be arranged separate from theV gas heater, the highly heated heating-gases being led to the tube nest I through The described gas heater -is suitatmospheres and more. If the heating gas and the gas to be heated have about the same Ypressure, the construction of the tube nests, already relieved by the yielding form of the U-bend is fnot subjectedtoanyadditional stresses. The total internal pressure is then taken by the pressure jackets. For increasing the safety of the con- Vstruction and improving the eiciency, insulatical weight-carrying pressure jackets, a rigid U- bend beneath said jackets connecting them in se- 3 ries, va vertical tube nest within each of said jackets, a yielding U-bend mounted with clearance within said rigid U-bend connecting said tube nests in series, means for supporting said jackets yieldingly on a xed base whereby the distance.V separating them can change with expansion changes in said rigid U-bend, a gas-tight seal between the periphery of the upper tube plate of each tube nest and its associated pressure jacket, a burner and combustion chamber supported on one pressure jacket and arranged to deliver the combustion products to a confined space above thev upper tube plate therein, and a collecting chamber and ilue supported on the other pressure jacket above and in communication with the upper tube plate therein. f

2.'A furnace according to claim 1 ingwhich the tube nest within the burner-supporting pressure jacket is supported through its lower tube plate by attachment to the'lower end of a guide jacket surrounding said tube nest, said guide jacket is supported at its upper end by, within and spaced from the walls of said pressure jacket, the combustion chamber is supported by,A within and spaced from the walls of said pressure' jacket above the upper end of said guide jacket with its delivery opening downward, and a sliding joint conduit connects said deliveryopening to the upperface of the'upper tube sheet. Y

3'. A furnace according to claim 2 in which an inlet for combustion air under pressure enters the burner-supporting pressure jacket above the upper tube plate seal, the burnerrenters the top ofthecombustion chamber, and air entryropenings in the combustion chamber wall areV provided around said burner and adjacentthe delivery'opening.

4. In a gas heater of the type'which includesa heating-gas flow-conductor enclosed in a heatedgas now-conductor, said heating-gas ilow-conductor including two vertical geometrically parallel tube bundles and a rst U-bend connecting the bottoms of said tube bundles in flow series and said heated-gas flow-conductor including o two geometrically parallel pressure jackets, each of which surrounds a different one of Asaid tube bundles, and a second U-bend surrounding said rst U-bend and connecting said jackets in iiow series, the improvement in which Ythrough its lower tube plate by the jacket surrounding it. j

6. A gas heater according to claim 4 in which the'joints connecting the second U-bend theV 5 pressure jackets are arranged higher than the joints connecting the rst U-bend to the tube bundles.

7. A gas heater according to claim 6 in which the clearance between the first and second U- 5 bends is sufcient to permit said second U-bend, after disconnecting the joints thereof, to be lowered a distance sufcient to give access to the joints of said :tirst U-bend.

10 WALTER HUBER.

REFERENCES CITED The following references are of record in the 15 file of this patent:

UNITED STATES PATENTS Number Number Name Date Price Aug. 24, 1926 Worden May 3, 1927 Smith Dec.4 17, 1928 Tielkemeyer Mar. 18, 1930 Jacocks Feb. 24, 1931 Ewing Nov. 24, 1931 Lockhart Nov. 7, 1933 McNeal Nov. 27, 1934 Wiederkehr Sept.. 18, 1945 FOREIGN PATENTS Country Date Great Britain Aug. 27, 1925 Great Britain Sept. 27, 1928 

